Operators

Operators are symbols that perform actions on values and variables. Python groups them into several categories.

Arithmetic Operators

Used for math calculations:

Operator	Name	Example	Result
+	Addition	3 + 5	8
-	Subtraction	7 - 2	5
*	Multiplication	4 * 6	24
/	Division	8 / 2	4.0 (always float)
%	Modulus	10 % 3	1 (remainder only)
//	Floor Division	15 // 4	3 (rounds down, drops decimal)
**	Exponentiation	2 ** 3	8 (2 to the power of 3)

Modulus (%) — Returns only the remainder after division. Useful for checking if a number is even or odd:

print(10 % 2)   # 0  → even (no remainder)
print(10 % 3)   # 1  → 3 goes into 10 three times with 1 left over

Floor Division (//) — Divides and drops everything after the decimal point:

print(15 // 4)  # 3  → would be 3.75, but floor division drops the .75

Assignment Operators

Used to assign or update a variable's value. The shorthand versions (+=, -=, etc.) are very common in loops:

Operator	Example	Same As
=	a = 12	Set a to 12
+=	a += 7	a = a + 7
-=	a -= 7	a = a - 7
*=	a *= 7	a = a * 7
/=	a /= 7	a = a / 7
%=	a %= 7	a = a % 7
//=	a //= 7	a = a // 7
**=	a **= 7	a = a ** 7

# Common use: incrementing a counter inside a loop
count = 0
count += 1   # same as count = count + 1

Comparison Operators

Used to compare two values. The result is always a bool — either True or False:

Operator	Meaning	Example
==	Equal to	x == 5
!=	Not equal to	x != 5
>	Greater than	x > 5
<	Less than	x < 5
>=	Greater than or equal	x >= 5
<=	Less than or equal	x <= 5

⚠️ A common mistake: using = (assignment) instead of == (comparison) inside an if statement will cause a SyntaxError or unexpected behavior.

Logical Operators

Used to combine multiple conditions together:

# and — BOTH conditions must be True for the whole thing to be True
if x > 0 and x < 10:
    print("x is between 0 and 10")

# or — AT LEAST ONE condition must be True
if x < 0 or x > 100:
    print("x is out of normal range")

# not — reverses/flips the condition
if not device_status == "online":
    print("Device is not online")

Membership Operators

Used to check whether a value exists inside a collection (list, string, dictionary, set, etc.):

devices = ["router", "switch", "firewall"]

if "router" in devices:
    print("Router found in list")       # This runs

if "printer" not in devices:
    print("Printer is not in the list") # This also runs

Identity Operators

Used to check whether two variables point to the exact same object in memory — not just the same value:

x = [1, 2, 3]
y = x           # y points to the SAME object as x

print(x is y)       # True  — same object in memory
print(x is not y)   # False

a = [1, 2, 3]
b = [1, 2, 3]       # a and b are separate objects with equal values

print(a is b)   # False — different objects, even though values match
print(a == b)   # True  — values are the same

Key rule: Use == to compare values. Use is only when you specifically need to check if two variables reference the same object. is not is common for checking if x is not None.